A New Labdane Diterpene from the Aerial Parts of Chloranthus serratus

A new labdane diterpene (1) and five known compounds (2-6) were isolated from the aerial parts of Chloranthus serratus. The gross structure of compound 1 was resolved by NMR and HRESIMS data. The absolute configuration of 1 was determined by comparing CD spectrum and specific rotations with those of the co-isolated known analogue 2. The known compounds were identified to be agathic acid (2), altechromone A (3), chlorajapolide F (4), shizukanolide (5), and chloranthalactone E (6) by comparing the NMR data with those in the literature. All compounds were evaluated for their inhibitions against NO production in LPS-activated RAW 264.7 macrophages, compounds 2 and 6 showed moderate inhibitions with IC50 values of 45.2 +/- 1.2 and 35.3 +/- 0.9 mu M.